Phosphodiesterases are known to regulate cyclic AMP, and phosphodiesterase 4 (PDE4) has been shown to be the predominant regulator of cyclic AMP in respiratory smooth muscle and inflammatory cells. Inhibitors of PDE4 are useful in treating a variety of diseases, including allergic and inflammatory diseases, diabetes, central nervous system diseases, pain, and viruses that produce TNF.
Amino-substituted quinolyl PDE4 inhibitors are disclosed in U.S. Pat. No. 5,804,588; sulfonamide-substituted quinolyl PDE4 inhibitors are disclosed in U.S. Pat. No. 5,834,485; and (benzo-fused)heteroaryl-substituted PDE4 inhibitors are disclosed in U.S. Pat. No. 6,069,151.